The present invention relates to a magnification correction system for use with optical equipment in general and, more particularly, to a zoom lens system which compensates for changes of focus size in an automatically focused motion picture or television camera.
The visual effect which is exhibited by a lens system when focused on a far subject and then refocused on a more near subject or vice versa is a change in the magnification. This can produce effects such as causing an object which appears in a picture quite close to the edge thereof to move into and out of the field of view as the camera alternately focuses on near and far subjects. Motion pictures taken without any correction for this magnification difference can be considerably disturbing and this is particularly true of photographic or television cameras which include automatic focusing since transitions from near to far objects is otherwise very smooth.
The present invention incorporates a zoom lens system which operates in cooperation with the movable or taking lens of a camera or other optical system so that changes in the position of the taking lens, as for example under the operation of the autofocus equipment, causes a corresponding change in the zoom lens system to compensate for the change in magnification.